Types of Research Design

By Centre for Health Communication and Participation La Trobe University, Australasian Cochrane Centre [CC BY-SA 3.0], via Wikimedia CommonsThere are various types of research design and the selection of a suitable study design depends on the field of study as well as the topic of the research. Some types of research design best suit in pure sciences field, while other can be best applied to social sciences, behavioral science, and marketing. These different types of research design can be categorized on various basis, one such categorization is as follows.

Types of research design:

Below some types of research design and their characteristics have been mentioned. It should be noted that each type of the research design has its own advantages and disadvantages. The researcher does not select a research design because it has several advantages but because it is most suitable types of research design for his study. Some types of research design are most suitable for the field of medical science, other types of research design are suitable for marketing, other for psychology and behavioral sciences. So the researcher should have knowledge of all types of research design before selecting one for his study.

The cross-sectional study design

The cross-sectional study designs are most commonly used in social sciences, behavioral sciences and marketing. In cross-sectional study design, the researcher aims at finding out the characteristics of a population by taking a cross-section of that population. The study is conducted once by taking a cross-section of the population. The method of designing this study is simple, the researcher determines the population to be studied and draws a sample from that population. The respondents are asked question using any one of the social science data collection tools. The answers of the respondents reflect the attitude of the respondents towards some service, idea or situation. The cross-sectional study is conducted once so there is no before-and-after study involved in it.

There are various advantages of cross-sectional study design: Cross-sectional studies are relatively easy to conduct and they are easy to analyze, they are conducted at one time so they are not time-consuming, the sample can be drawn using any of the appropriate methods. The drawback is that in cross-sectional study design the researcher cannot determine the pattern of change before and after the test. The study is conducted once, therefore, the researcher cannot determine any change in the observations of the population.

The before-and-after study design

See page for the author [CC BY 4.0], via Wikimedia CommonsThe before-and-after study design is most suitable to measure the change in a situation, phenomenon or attitude. In this study design, the researcher undertakes one experiment or observation of the population before administering the test and another observation or experiment after administering the test. The before-and-after test helps the researcher in understanding the impact of the service or situation. Primarily, before-and-after study design is similar to the cross-sectional study design, the only difference being that it is conducted twice. The before-and-after study design is simple and it still does not take into account the external variables that might affect the results of the second observation or experiment that the researcher is going to record. Some examples of before-and-after study designs are illustrated here in pictures.
See page for author [CC BY 4.0], via Wikimedia CommonsThere are various advantages of before-and-after study design, the main advantage is that it is a pre-test/post-test design, it can measure change. However, there are various drawbacks of this study design. This study design is expensive to undertake because of the re-administration of the test. To re-administer the test the researcher has to collect the population again and make a suitable environment which might be costly. It is also a time-consuming since the researcher needs to wait for the intervention of the program to retake the test. This study still lacks a control on the other variables that might affect the results or the responses along with the independent variable. There might be other extraneous variables that affect the responses and the researcher will attribute the change to the independent variable, which is not correct. The intervention of the program can take too much time and hence there can be possible changes in the population in terms of age or maturity. A change in the population can also affect the responses the respondents give in the re-test.

The longitudinal study design

By Avon Longitudinal Study of Parents and Children (ALSPAC web site) [CC BY-SA 3.0], via Wikimedia CommonsThe longitudinal study design has the capability of determining the change pattern in human behavior, situation or phenomenon over a period of time. The pattern of change in attitudes etc cannot be studied using before-and-after study design. In longitudinal studies, the researcher keeps a contact with the target population over a period of time. He makes observations or makes experiments at intervals of time and records them. This helps the researcher in understanding the pattern of change or how the attitudes have been changed over a period of time.

The major disadvantage of the longitudinal study is that the respondent might lose interest and he may give responses that do not truly represent his thinking. The other disadvantage can be that the population may not remain same and this will affect the results. However, in certain fields, longitudinal study is very effective to conduct because it determines the change pattern over a period of time.

The retrospective study design

The retrospective studies as the name suggest studies a prevalence of a situation, phenomenon, or an issue that has happened in the past. It is a descriptive study and it uses the available information from the past in the form of books, magazines, journals, newspapers, government records, diaries or letters. Sometimes if the person who encountered that situation can also be asked for the information to conduct a retrospective study.

The retrospective study design has its own advantages and disadvantages. A retrospective study design is a descriptive study design, hence, it can be used only to investigate about some topic descriptively. This study uses secondhand information or secondary sources so the reliability of the information is not much. The reason for conducting a retrospective study is that in the absence of primary data, the researcher cannot use any other method to collect the evidence

The prospective study design

The prospective study design studies a situation, phenomenon or a problem that might occur in the future. The prospective study design is like retrospective study design, but it focuses on predictions about the future rather than about the past happenings.

The retrospective-prospective study design

The retrospective-prospective study design studies a situation, event or a phenomenon as it happened in the past, in addition, it forecasts about the same situation if it happens in the future.

The experimental study design

By The U.S. Food and Drug Administration (Toxicology Research at FDA (NCTR 1412)) [Public domain], via Wikimedia CommonsThe experimental study design is the most comprehensive study design, it investigates the problem, phenomenon or a situation by identifying dependent and independent variable. The researcher also identifies the extraneous variables and aims at controlling the extraneous variables throughout the experiment. The experimental study design utilizes first-hand information and is categorized as the primary source of information. In medical sciences and other branches of pure sciences, experimental study design is the most preferred study design.

These are few major types of research design and there are several other minor types of research design that are used in specific studies.